1. Field of the Invention
The invention relates to a method of manufacturing a chip type piezoelectric resonator for use in a piezoelectric filter, an oscillator or the like.
2. Description of the Prior Art
There has been proposed a chip type piezoelectric resonator constructed as in FIG. 3 and a method of manufacturing the same effectively.
In FIG. 3, 1 shows a piezoelectric resonator which comprises a piezoelectric device 5A which includes a piezoelectric substrate 2 provided on both of its sides with a plurality of vibrating electrodes 3 and input/output electrodes 4, respectively. Layers each comprising a first sealing substrate 6 are placed over and adhered to both sides (top and bottom) of the piezoelectric device 5A followed by forming a pair of outside electrodes 7 each electrically communicating with the input/output electrodes 4. Further a second sealing substrate 8 is adhered to both exposed lateral side surfaces (front and back) of the piezoelectric device 5A thereby sealing both of its lateral sides.
The vibrating electrodes 3 are located in a vibration cavity 9 to prevent vibration from being damped, and the vibration cavity 9 is sealed at both ends by an adhesive 10. Each vibration cavity 9 is a gap which is defined between the piezoelectric substrate 2 and the first sealing substrate 6. The gap's height is equal to the thickness of the coated adhesive 10.
The method of manufacturing the above piezoelectric resonator 1 will be detailed with reference to FIGS. 1A, 4A and 4B.
A piezoelectric device 5A constituting a principal portion of the piezoelectric resonator 1 is made, as shown in FIG. 4A, by providing the piezoelectric substrate 2 made of piezoelectric ceramics or the like on both its sides with the electrodes 3 and 4 by sputtering, vacuum deposition, or printing and baking of conductive paste, or the like. A plurality of piezoelectric devices 5A (see FIG. 1A) are comprised in the piezoelectric device substrate 5. The opposing (overlapping) portions of the electrodes in the piezoelectric devices 5A at the top and bottom sides of the piezoelectric device substrate 5 (as seen in the figures) form the vibrating electrodes 3, and the remaining end parts of the piezoelectric devices 5A which are not overlapping with each other form the input/output electrodes 4. The first sealing substrate 6 made of ceramics is placed on and adhered to both side surfaces of the piezoelectric device substrate 5 to form the vibration cavity 9 along each vibrating electrode 3 of the piezoelectric device substrate 5 comprising the plurality of piezoelectric device 5A, thereby forming a substrate-layered member 11. The substrate-layered member 11 is cut along the lines C--C and D--D in FIG. 4B to obtain an individual resonator element 12. The outside electrodes 7 are formed at both lateral ends of the resonator element 12 so as to electrically communicate with the input/output electrodes 4 which extend to those ends. Also, the second sealing substrates 8 are adhered to both lateral side surfaces of the resonator element 12 to seal the vibration cavity 9 and thereby form the piezoelectric resonator 1 of FIG. 3.